During the Vienna event, the ITUC was constituted on the basis of the merger of the International Confederation of Free Trade Unions (ICFTU) and the World Confederation of Labour (WCL).
The new federation will gather 166 million workers from 309 national trade union associations in 156 countries.
Upon the establishment of the new federation, Guy Ryder, who was on Wednesday appointed as the leader of the ITUC, said that the strong tradition of solidarity would continue.
Austrian President Heinz Fischer, addressing the estimated 1,600 delegates in Vienna, called giving workers a greater voice "an important and indispensable component of a democratic society," according to the Associated Press.
On 2 November, participants in the Vienna congress will discuss topics: "Cohesion and Chaos - Global Institutions", and "Global Trade Unions - Global Companies.
Pascal Lamy, the director-general of the World Trade Organisation, is expected to address the congress by video-link.